> Some time ago I posted a message regarding broken filament connections
>in a pair of 3-500Z, and asked the proper method for resoldering their
>pins. I got the AG/Sn solder and resoldered them with care, they're
>working fine now. But, the internal fan, although it runs, is
>overheating. My first question is, maybe this overheating is due to our
>50 Hz line frequency?, anyway, the amp has been running many years as it
>was with the same fan, we noted this now. I measured line current at 110
>VAC and it takes nearly 1,5 Amps. A lot.
? a 12v DC brushless fan would be more efficient.
>
> The last question is about final tuning settings; the owner use it
>always at CW plate voltage (1800 VDC with no load, 1600V at 500 watts
>out), he don't want to "pull" it at 2500 VDC (SSB mode). The user's
>manual state to run grid current from 200 upto 400 mA. We found tuning
>conditions with above stated power output, 500 mA plate current and grid
>current of 200 mA, in the lower limit.
> Could a lower Ig (maybe 100...150 mA, with less drive, taking in care
>all other tuning settings are well adjusted) make any harm to the
>tubes?, or the manual recommendations are regarding best possible
>linearity and/or efficiency?.
>
? 75mA per tube is needed for good linearity.
> ...
Rich, AG6K, 805-386-3734, www.vcnet.com/measures
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